(a) Field of the Invention
The invention relates to the production and characteristics of anti-teicoplanin polyclonal antibodies and immunoassays for measuring teicoplanin.
(b) Description of Prior Art
Teicoplanin is the international non-proprietary name (INN) of the antibiotic substance formerly named teicomicin which is obtained by cultivating the strain Actinoplanes teichomyceticus (nov. sp. ATCC 31121) in a culture medium containing assimilable sources of carbon, nitrogen and inorganic salts. Canadian Patent Application 2,003,325 laid-open on May 22, 1990, in the name of Gruppo LePetit S.p.A., describes a process for preparing teicoplanin amides.
Teicoplanin, a novel glycopeptide antibiotic of the vancomycin class, is undergoing clinical investigation in some countries for the treatment of gram-positive infections.
Several methods of measuring serum teicoplanin or monitoring its therapeutic concentrations, have recently been developed, including microbiological assay, high pressure liquid chromatography, a solid phase enzyme receptor assay, a receptor-antibody sandwich assay and a fluorescence polarization immunoassay. Each method has some advantages and some limitations.
Methods known so far for determining antibiotic substances and in particular teicoplanin and the other antibiotics of the vancomycin class are mainly based on HPLC, and bioassays on susceptible microorganisms. In view of the current therapeutic use or advanced clinical study of some of these antibiotics, there is a need for assay methods for their determination in fluids, especially biological fluids, which would be specific, rapid, easy, reliable and suitable for automation.
In particular, the detection of these substances in body exudates, bronchial expectorates, pus, skin samples from burned patients, etc., is particularly difficult with known techniques since false-positive results are often obtained.
Canadian Patent 1,276,880 issued on Nov. 27, 1990, in the name of Gruppo LePetit S.p.A. describes a sandwich assay for determining a substance capable of binding to a D-Alanyl-D-Alanine dipeptide or a D-Alanyl-D-Alanine carboxy terminal oligopeptide. This sandwich assay can be used to determine a glycopeptidic antibiotic of the vancomycin class or a derivative or aglycon thereof. The assay combines the high selectivity of a suitable D-Alanyl-D-Alanine derivative for the antibiotics of the vancomycin class and the specificity of an antibody directed against the antibiotic of the class to be tested. The antibodies specifically directed to the substance to be determined are antibodies elicited in an animal by injection of a suitable conjugate of the substance to be tested. The antibody production was found unacceptable when following conventional antisera techniques. Several attempts were made to enhance the antibody production, such as combining the antigen to a protein such as bovine serum albumin (BSA). The antibody production has not reached a sufficient level to be commercially useful.
Antibodies to antibiotics are necessary for immunoassays to analyse cross-reactions and for other purposes. Several recent communications deal with the production of antibodies in rabbits and humans immunized with various antibiotics (penicillins, cephalosporins, aminoglycosides, clindamycine, amphotericin-B, etc.)
In these studies, antibiotics were conjugated with suitable proteins carriers such as bovine or human gamma-globulin and then emulsified in Freund's complete adjuvant. The quantity, titer and specificity of these antibodies appeared to be sufficient. However, antibody production in rabbits with antibiotics alone appeared to be insufficient. Some antibiotics showed the property of haptens. Others such as moxalactam, were much less immunogenic in rabbits.
It would be highly desirable to be provided with a method of producing anti-teicoplanin antibodies to a high level.
Liposomes are known as adjuvant in antigens preparations to enhance antibody response. Liposomes are concentric spheres consisting of phospholipid bilayers separated by aqueous compartments.
It would be highly desirable to be provided with a method of producing antibodies to antibiotics using liposomes.
It would be highly desirable to be provided with an antibody against teicoplanin which could be used in an immunoassay for measuring the amount of teicoplanin present in a sample.